Tank level monitoring and timely reporting of information are critically important both economically and environmentally for both consumer and commercial applications. On the consumer side, tank level monitoring, for example, for heating fuel storage tanks ensures that proper deliver of additional heating fuel may be accomplished before the consumer runs out the tank goes empty. In commercial applications, such as a gas station, tank level monitoring is also used to ensure that the gas station does not run out of gas before another delivery of fuel may be accomplished. If such a situation were to occur, this would result in a of loss revenue for the gas station and an inconvenience for consumers. From the ecological stand point, tank level and spill monitors are used to identify leak conditions, that if left unchecked, could result in environmental damage.
In the past both consumers and commercial operators were required to manually check the tank levels, either by reading a gauge or using a dip stick, to determine the level of fuel or other substance in the storage tank. The users would then be required to call for additional fuel or other substance to be delivered to refill the tank under a will-call system. However, if the user were to forget to check the tank or misjudge when a call for re-supply should be made based on their usage, the tank could run empty before a re-supply arrives.
To overcome this problem modern tank level monitoring systems automate the monitoring and reporting of the tank level. This allows distributors to use computerized supply systems to schedule deliveries to prevent their stations or customers from running dry. As an example of such a modernized system, many gas stations utilize tank level monitors to monitor the level of fuel in both of their storage tanks, one for regular and one for premium-(mid-grade being a combination of the two). These tank level monitors are than hard wired to a communication module that reports the tank level information to a distributor's supply computer to automate the scheduling of deliveries of fuel. Such a communication module may provide this information over traditional telephone lines via a modem that dials in to the distributions system computer.
Recently, these systems have begun to us a constellation of low-Earth orbit (LEO) satellite systems to relay such information. Such systems have found favor with large oil companies because as it allows them to collect information from thousands of locations at a central point. This information may then be used not only to schedule fuel deliveries at a local level, but also to measure profitability, usage patterns, etc. for their entire distribution network.
A problem with such a system, however, lies in the use of the hard wired connection between the tank level monitors and the communications module. Because the tank level monitors are monitoring a volatile fuel, safety requirements for the communications wiring leading from the tank level monitors to the communications module requires isolation, grounding, and barrier techniques be used to reduce the risk of propagating an electrical charge to the storage tanks. As may well be imagined, conducting a lighting strike along the communications line to a fuel storage tank is not desirable. Additionally, since the typical gas station only includes two storage tanks, the amount of information needed to be transmitted via the LEO satellite system is relatively small. As such, and even though usage of the LEO satellite system is charged by the bit of information transmitted, these systems simply transmit the data monitored from each tank.
Another system that is currently available for more remotely located, single tank storage instillations provides a tank level monitor and satellite communications module in a single integrated assembly. This stand alone unit provides a single monitor/uplink per storage tank. This integrated assembly periodically checks the tank level and transmits this information on a scheduled basis via the LEO satellite to its remotely located monitoring center.
While such a system is good for single tank remote locations, it becomes prohibitively expensive if multiple tanks at a particular location need to be monitored. This is because each tank level monitor also integrates the satellite communications module that enables it to report its data to the LEO satellite system. Further, if volatile fuels or chemicals need to be monitored, incorporation if the satellite communications module on the tank raises safety concerns that will also drive up the costs of the housing and design to ensure the assembly's intrinsic safety. Additionally, since each tank level monitor transmits its own data via the LEO satellite system, the cost for transmitting the amount of data that would be generated at a storage tank farm is prohibitive.
While each of these systems provides an improvement over the previous requirement that the tank level be manually checked and reported, each introduces cost and safety concerns, particularly for large, remote storage locations having multiple storage tanks for which the tank level needs to be monitored. There exists, therefore, a need in the art for a tank level monitoring system that provides intrinsic safety, cost efficiency, and the ability to report monitored information to and receive commands from remote locations worldwide.
These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.